Military and law enforcement organizations often seek to employ low-energy training ammunition having a shorter range and lower terminal effect than standard, service ammunition. In order to facilitate such training, it is desirable to modify the standard or “stock” firearm in order to be able to reliably fire this low-energy training ammunition. Many thousands of weapon conversion kits have been produced and sold in recent years and due to the increasing use of metal injection molded (MIM) components and light-weight polymer materials for weapon receiver and frame parts, more complex geometrical weapon designs are now possible. This has led to more complicated conversion kit designs, which now more frequently require changing out the service or stock weapon slide as well as changing out the original barrel for a training barrel.
Currently known conversion kits often face reliability problems due to improper ejection of the fired cartridge case. Since the reduced energy cartridges are ejected from the converted weapon using the straight blowback principle, the energy required to cycle the weapon is generated only from the rearward piston motion of the reduced energy cartridge case against the weapon breech face (see, for example, U.S. Pat. No. 5,359,937).
Furthermore, because the converted weapon includes a conversion barrel that is not locked with the slide of the service pistol frame, the training barrel moves differently than a service barrel during use, which creates an offset between the firing pin/striker and the centerfire primer of the training cartridge.
During normal use, firing a standard, unconverted weapon will cause the muzzle end of the service barrel to tilt upward after chambering of the standard ammunition, whereas the unlocked training barrel makes no tilting movement upward, which makes feeding the training ammunition into the conversion kit chamber more challenging.
When conventional ammunition is fired from a weapon with a standard barrel and slide, the chamber end tilts downwards for feeding of ammunition, it thus presents the chamber in an optimal position versus the weapon magazine for feeding of the cartridge, then it tilts upwards again for the striker or firing pin to properly impact the centrally located primer of a cartridge in the chamber. After firing, the barrel moves rearwardly with the slide, then unlocks and the chamber end of said barrel tilts downwards once again so that the fired cartridge case can be properly extracted, can hit the ejector, and can be finally ejected from the weapon (when the slide recoils rearwardly). This normally occurs with conventional ammunition with the assistance of an ejector that is part of the weapon frame assembly. The position of the ejector ensures that it is able to impact sufficient surface area of the rim of the fired conventional cartridge case such that it is reliably ejected from the ejection port of the weapon.
In order for a converted weapon to function reliably for training, it must be capable of properly feeding the training ammunition from the magazine to the feed ramp. In this regard, some weapon conversion kits require an additional, detachable feed ramp (see, for example, U.S. Pat. No. 6,276,252) for the ammunition to be properly positioned for the firing pin to properly impact the centerfire primer for reliable ammunition function and then finally for the stock ejector to properly hit the cartridge case rim of the fired shell casing afterwards for proper ejection. All of the resulting alignment details are more complex with a non-tilting conversion barrel, leading to a range of design compromises.
First, the firing pin in such conversion kit sometimes needs to be offset (with respect to the stock firing pin) to ensure sufficient impact on the primer of the training ammunition. This often requires unusual firing pin designs and/or positioning to mitigate the lack of barrel tilting, but also increases production costs while creating potential design weaknesses. Second, the non-tilting barrel presents less surface area for the ejector to impact the cartridge case of the fired training round.
In order to eject the fired cartridge case properly, there must be sufficient material overlap between the rim of the cartridge case and the ejector. This is not always the case with converted weapons because the position of the fired cartridge case is no longer in the same plane as the ejector and is thus a potential cause for increased stoppages and reduced weapon reliability.
There is a long-felt need for conversion kits that provide proper ejection, but which also permit proper firing pin/striker impact on the training ammunition primer. Off-center impacts are often the cause of misfires, which cause weapon stoppages. The majority of pistols have a fixed ejector that is attached to the weapon frame, a part of the weapon which is not normally modified for training purposes. Since it is normally fixed, the ejector position is a given and thus the firing pin (or striker) becomes the component of the conversion kit that is moved as required to compensate the offset (as much as physically possible) for more reliable functioning. However, the maximum possible distance that the firing pin can be offset in the training slide is limited by the amount of material in the weapon, due to geometrical constraints.
Accordingly, there is a trade-off between having a good, solid firing pin impact on the centerfire primer and being able to reliably eject the cartridge case, due to the limits of weapon geometry.
The firing pin/striker of an unmodified weapon is oriented on the central axis of the service ammunition when the ammunition is present in the chamber of the tilted barrel and thus is in direct line with its centrefire primer. This is not the case with a weapon with a non-tilting conversion kit and so even offset firing pins can still generate insufficient primer strikes and thus misfires.
Even if primer initiation and cartridge case ejection is successful, the ejection energy may vary due to design constraints imposed by the geometry of the converted weapon. Marginal contact between the ejector and the cartridge case may result in weak ejection from the training weapon. Weak cartridge case ejection is a symptom of a marginal design condition and possible stoppages to come and this affects the trainee's perception of the weapon performance and reliability and thus the realism of the training.
Due to the geometry constraints of some converted weapons, it has previously been required to provide modified firing pins/strikers with conversion kits in order to attempt to overcome the offset caused by the non-tilting barrel to properly impact the primer. These unique conversion kit firing pins/strikers are sometimes positioned on an angle (versus the longitudinal axis of the conversion slide) to assist with firing pin impact on the primer. Sometimes the conversion kit firing pins tips have required a modified tip geometry to compensate for the offset, sometimes resulting in an asymmetrical in form, having a “shark fin” design or being completely offset, with the firing pin tip in a plane parallel to but below the central longitudinal axis of the firing pin. The shark fin firing pin tip design has the disadvantage of presenting a sharp tip (rather than the standard round head tip design) which has been shown to occasionally cause pierced primers, which is unsatisfactory. The offset firing pin tip designs also have the disadvantage of generating a bending moment on the offset arm of the firing pin, which can lead to breakages of the firing pin.
Another method that has been introduced to improve cartridge case ejection is to fix (by welding or by pinning) a new, supplementary ejector directly onto the conversion barrel, at the lower chamber end. This method helps ensure proper contact with the cartridge case rim, but has the disadvantages of being more costly to produce and of introducing a long, thin element that can be easily bent or broken by the trainee during the process of converting the weapon for training or when restoring it to operational service condition. Further, such ejectors are located inside the frame or slide of the stock weapon, which has its own inherent geometry variations, and thus is also limited in its application due to spatial constraints in some weapons.
Accordingly, there is a long-felt need for firearm conversion kits with improved ejector systems that can address the above limitations of the prior art. Other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.